This invention relates to automotive headlights, and more particularly, to a headlight in which the reflector is contoured to meet the required light specifications and the lens is replaced with a clear cover plate which can be placed at any angle which is aerodynamically desirable.
Sealed beam automotive headlights include a paraboloidal reflector which collects light from an incandescent filament bulb and directs it toward a lens. The lens has flutes which shift and spread the light into a beam pattern which meets the specifications set by the Society of Automotive Engineers. Because the standard lens is the optically active element having fluting with flute risers and edges, its positioning with respect to the bulb and reflector is critical. Desirably the position of the lens should be nearly normal to the light emanating from the bulb and reflector, since riser glare becomes worse when the lens is slanted at an angle thereto. That is, the lens fluting produces uncontrolled light, known as glare, from the flute risers and edges. In many instances, it would be desirable to have a headlight with a slanted front surface which would give superior aerodynamic performance. However, as noted above, with the optics in the lens and the resulting glare, it is not practical to provide such a slanted front surface which also would be desirable for reasons of style. It is the elimination of this type of glare while retaining the benefits of slanted lenses which is an object of this invention.
U.S. Pat. Nos. 153,341--Jacobsen and 1,346,268--Goodley show early attempts to produce lamps with the optics in the reflectors. U.S. Pat. Nos 3,511,983--Dorman and 4,149,277--Dorman, show more recent attempts to provide a lamp in which the reflector produces a desired light pattern. These reflectors are not suitable for meeting the more stringent automotive specifications.
"Computer Design of Automotive Lamps With Faceted Reflectors", Donohue and Joseph, J. of I.E.S./1972, pp. 36-42 describes an automotive lamp in which the reflector is divided into segments (facets) in such a manner that the reflector alone produces the pattern and lens fluting is eliminated. The many facets, as shown in FIG. 12 of that article, have sharp edges and discontinuities between them. Since each facet is a paraboloidal surface, the intersections, or junctions, between the surfaces necessarily are not smooth. Because of this, the fabrication of such a reflector is quite difficult. These reflectors may be formed from any suitable material such as glass, plastic or metal. It is quite difficult to form the surfaces having the discontinuous junctions shown in FIG. 12 of that article.
It is an object of the present invention to provide an automotive headlight reflector which directs light in a pattern which meets automotive specifications and which has smooth, continuously joined surfaces which facilitate fabrication of the headlight.